Polyphenyl thioether lubricating compositions

ABSTRACT

PHENOXYPHENYLPHOSPHINIC ACIDS AND LUBRICATING COMPOSITIONS COMPRISING POLYPHEYL THIOETHERS, POLYGENYL ETHERS-THIOETHERS OR MIXTURES THEREOF AND SMALL AMOUNTS OF SAID ACIDS HAVE IMPROVED LUBRICATING PROPERTIES OVER WIDE TEMPERATURE RANGES.

United States Patent US. 'Cl. 252--46.7 7 Claims ABSTRACT OF THEDISCLOSURE Phenoxyphenylphosphinic acids and lubricating compositionscomprising polyphenyl thioethers, polyphenyl ethers-thioethers ormixtures thereof and small amounts of said acids have improvedlubricating properties over wide temperature ranges.

This invention relates to phenoxyphenylphosphinic acids and to improvedlubricating compositions compris ing polyphenyl thioethers, mixedpolyphenyl ethers-thioethers and mixtures thereof, containing from 3 to8 aromatic groups and a small amount of said phenoxyphenylphosphinicacid as a lubricating additive.

Polyphenyl thioethers and polyphenyl ether-thioether combinations havefound wide application as functional fluids due to their excellentthermal stability and lubricity. For example they have been found to bevaluable as hydraulic fluids and as lubricants in motor operation,particularly in jet engines.

Development of synthetic base stocks such as the polyphenyl thioetherhas provided lubricant fluids which are useful at elevated temperaturesuch as 400 to 500 F. It is known that one of the aspects in which thepolyphenyl thioether base stocks are considered deficient is in theirlubricating characteristics. These lubricating characteristics includethe load-carrying abilities and wear properties, especially underconditions of high pressures and temperatures reached in the advancedesign aircraft engines. Thus there is a demand for polyphenylthioethers having improved lubricity properties.

An object of this invention is to provide novel phenoxyphenylphosphinicacids having excellent lubricating additive properties.

Another object of this invention is to provide improved lubricatingcompositions comprising polyphenyl thioethers, polyphenylether-thioethers, or mixtures thereof and a small amount of aphenoxyphenylphosphinic acid.

These and other objects will become evident upon consideration of thefollowing specification and examples.

The phenoxyphenylphosphinic acids of this invention can be representedby the formula wherein R and R are alkyl of not more than 4 carbonatoms, haloalkyl of not more than 4 carbon atoms and 3 halogen (Cl, Brand F) atoms, halogen (Cl, Br and F), hydroxyl or phenyl, and m and aare integers from 0 to 3.

Representative groups for R and R in the above formula include alkylsuch as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl and t-butyland haloalkyl such as chloromethyl, bromomethyl, chloroethyl,bromoethyl, trichloromethyl, tribromomethyl, dichloroethyl, chloro-3,714,643 Patented Jan. 30, 1973 n-propyl, bromo-n-pro'pyl,bromo-n-butyl, bromo-tertbutyl, 1,3,3-trichlorobutyl and1,3,3-tribromobutyl.

Phenoxyphenylphosphinic acids represented by the above formula include,for example,

p-phenoxyphenylphosphinic acid, o-phenoxyphenylphosphinic acid,m-phenoxyphenylphosphinic acid, p-(p-rnethylphenoxy)phenylphosphinicacid, 0- (p-methylphenoxy) -p-methylphenylphosphinic acid,p-(o-methylphenoxy)phenylphosphinic acid, p-(p-ethylphenoxy)phenylphosphinic acid, p- (o-ethylphenoxy phenylphosphinic acid,o-(o-ethylphenoxy)phenylphosphinic acid, p- (p-butylphenoxy)phenylphosphinic acid, p-(p-chlorophenoxy)phenylphosphinic acid, 0-(m-chlorophenoxy) phenylphosphinic acid, p- (p-phenylphenoxy)phenylphosphinic acid, o-(p-phenylphenoxy)phenylphosphinic acid, p-(o-hydroxyphenoxy phenylphosphinic acid, p- (m-bromophenoxyphenylphosphinic acid, p- (p-hydroxyphenoxy) phenylphosphinic acid,o-(m-phenylphenoxy)-phenylphosphinic acid 0- p-methylphenoxy-m-methylphenylpho sphinic acid, 0- (p-methylphenoxy-m-chloromethylphenylpho sphinic acid,p-(p-methylphenoxy)-m-trifluoromethylphenylphosphinic acid, p-(o-butylphenoxy) -o-trifluoromethylphenylphosphinic acid, m-(o-phenylphenoxy)-p-methylphenylphosphinic acid,m-(o-methylphenoxy)-o-butylphenylphosphinic acid,mo-chloromethylphenoxy) -o-methylphenylphosphinic acid, 0-(m-methylphenoxy ptrifluorometl1ylphenylphosphinic acid, 0-(m-hydroxyphenoxy) -p-hydroxyphenylpho sphinic acid, 0- m-phenylphenoxy)-m-chloromethylphenylphosphinic acid and pm-phenylphenoxy)-m-hydroxyphenylphosphinic acid.

The improved compositions of this invention comprise a major amount of apolyphenyl thioether-base fluid of the formula RY(R Y) R wherein R isphenyl, alkyl-substituted phenyl wherein the alkyl is of not more than 4carbon atoms, alkoxy-substituted phenyl wherein the alkoxy is of no morethan 4 carbon atoms or halogenated phenyl wherein the halogen isbromine, fluorine or chlorine, R is phenylene, alkyl oralkoxy-substituted phenylene where the alkyl contains no more than 4carbon atoms or halogenated phenylene wherein the halogen is fluorine,bromine or chlorine, and Y is selected from oxygen and sulfur but atleast one of the Ys is sulfur and n is an integer having a value of 1 to6 and a lubricating additive amount of a phenoxyphenylphosphinic acid ofthe formula wherein R R m and a are as defined above. The compositionsof this invention have unusual ability to lubricate under high loads athigh temperatures.

The amount of phenoxyphenylphosphinic acid employed in the compositionsof this invention can range from about 0.01 to about 0.5% by weight. Itis preferred to employ the acids in the compositions of this inventionin amounts of from about 0.05 to 0.2% by weight based upon the totalcomposition.

The polyphenyl thioethers employed in the composition of this inventionhave from 3 to 8 benzene rings and from 1 to 7 sulfur atoms with thesulfur atoms joining the benzene rings in chains as ether linkages.

By the term polyphenyl thioether as used herein is meant a compound orphysical mixture of compounds wherein all of the Ys in the formula aresulfur. The term also includes those compounds which contain both oxygenand sulfur linkages between the benzene rings.

The compositions of this invention contain a major amount of thepolyphenyl thioether base stock, i.e., at least 50% by weight of thetotal composiiton comprises a polyphenyl thioether. It is preferred thatat least 60% by weight of the composition be a polyphenyl thioether basestock and even more preferred that at least 85% by Weight of the totalcomposition comprise a polyphenyl thioether.

Illustrations of the alkyl-substituents present in the phenyl andphenylene groups of the polyphenyl thioethers are for example, methyl,ethyl, propyl, butyl and the like. Illustrations of thealkoxy-substituents are, for example, methoxy, ethoxy, propoxy, butoxyand their isomers.

The compositions of this invention can also contain from 0.01 to 10% byweight of the total composition of a dialkyl hydrogen phosphite extremepressure additive. The dialkyl hydrogen phosphites useful are thosewherein the alkyl groups contain from 1 to 12 carbon atoms. The alkylgroups are for example, methyl, ethyl, propyl, isopropyl, butyl,sec-butyl, t-butyl, hexyl, decyl, isodecyl, dodecyl and the like.

Illustrative of the polyphenyl thioethers which can be employed as basestocks for the compositions of this invention are thebis(phenylmercapto)benzenes. For example m-bis phenylmercapto benzeneo-bis (phenylmercapto )benzene p-bis (phenylmercapto) benzene bis(m-phenylmercaptophenyl) sulfide bis (o-phenylmercaptophenyl) sulfidebis(p-phenylmercaptophenyl sulfide m-p henylmercaptophenyl)(o-phenylmereaptophenyl) sulfide pphenylmercapto-m-phenylmercaptodiphenyl sulfide o-bis (0-phenylmercaptophenylmercapto benzene p-bis(p-phenylmercaptophenylmercapto benzene p-bis(o-phenylmercaptophenylmercapto) benzene p-bis(n1-phenylmercaptophenylmercapto) benzene m-bis(p-phenylmercapctophenylmercapto benzene o-bis(p-phenylmeracptophenylmercapto benzene and the like and mixturesthereof.

Illustrative of the mixed polyphenyl ether-thioether compounds which canbe employed as base stocks in the compositions of this invention are forexample,

o-phenylmercapto-m-phenoxy benzene p-phenylmercapto-o-phenoxy benzenem-phenoxy-p-phenylmercapto benzene o-phenylmercapto-p'-phenoxydiphenylsulfide o-phenylmercapto-m'-phenoxydiphenyl sulfideo-phenoxy-m'-phenylmereaptodiphenyl sulfidem-phenoxy-p'-phenylmercaptodiphenyl sulfideo-phenoxy-p'-phenylmercaptodiphenyl sulfidep-phenoxy-p'-phenylmercaptodiphenyl sulfideo-phenoxy-o-phenylmercaptodiphenyl sulfide o,o'-bis (phenylmercapto)diphenyl ether o-phenylmercapto-m-phenylmercaptodiphenyl ethero-phenylmercapto-p-phenylmercaptodiphenyl ethermm-phenylmercaptophenylmercapto) (m-phenoxyphenylmercapto)benzene [m-(m-phenylmercaptophenylmercapto)phenyl][m-(mphenoxyphenylmercapto)phenyl] sulfide 3-(m-phenylmercaptophenylmercapto) -3'- (m-phenylmercaptophenoxy) diphenylsulfide 3,3-bis (m-phenylmercaptophenylmercapto) diphenyl ether 3-(m-phenylmereaptophenylmercapto -3'- (m-phenoxyphenoxy) diphenyl sulfide4- (m-phenylmercaptophenylmercapto -4-(m-phenylmercaptophenoxy) diphenylether 3- m-phenylmercaptophenylmercapto -3'- (m-phenoxyphenyl-mereapto)diphenyl ether 4,4'-bis(m-phenylmereaptophen'oxy)diphenyl sulfide4,4-bis (m-phenoxyphenylmercapto diphenyl sulfide 3-(m-phenoxyphenylmercapto) -3'- (m-phenylmercapto phenoxy) diphenylsulfide 3,3-bis (m-phenylmercaptophenoxy) diphenyl ether 4-(m-phenylmercaptophenylmercatpo -4- (m-phenoxyphenoxy )diphenyl ether 3-(p-phenylmercaptophenoxy) -3- (p-phenoxyphenoxy) diphenyl sulfide 3-(m-phenylmercaptophenoxy) -3'- (m-phenoxyphenylmercapto) diphenyl ether3 ,3 '-bis (m-phenoxyphenylmercapto diphenyl ether, and

3-(m-phenoxyphenylmercapto)-3'-(m-phenoxypl1enoxy)- diphenyl sufide.

In addition to the foregoing compounds, the phenyl and phenylene of suchcompounds can contain substituents, such as alkyl of l to 4 carbonatoms, alkoxy of 1 to 4 carbon atoms and halogen such as chlorine,bromine and fluorine. Examples of such compounds are as follows:

4,4'-'bis (m-tolylmercapto) diphenyl ether 3 3 '-bis m-tolylmere aptodiphenyl ether 2,4'-bis (m-tolylmercapto diphenyl ether 3,4-bis(m-tolylmercapto) diphenyl ether 3,3'-bis(p-tolylmercapto)diphenyl ether3,3 '-bis(xylylmercapto) diphenyl ether 4,4'-bis (xylylmercapto)diphenyl ether 3,4'-bis (xylylmercapto diphenyl ether 3,4'-bism-isopropylphenylmercapto) diphenyl ether 3,3 '-bis(m-isopropylphenylrnercapto diphenyl ether 2,4'-bis(m-isopropylphenylmercapto) diphenyl ether 3,4'-bis(p-tert-butylphenylmercapto diphenyl ether 4,4'-bis(p-tert-butylphenyl-mercapto diphenyl ether 3 3 '-bisp-tert-butylphenylmercapto diphenyl ether 3 ,3 '-bis(2,4-di-tert-butylphenylmercapto diphenyl ether 3,3'-bis3-chlorophenylmercapto) diphenyl ether 4,4'-bis 3-chlorophenylmercaptodiphenyl ether 3,3-bis (m-trifluoromethylphenylmercapto diphenyl ether4,4-bis (m-trifluoromethylphenylmercapto) diphenyl ether 3,4'-bis(m-trifluoromethylphenylmercapto diphenyl ether2,3'-bis(rn-trifiuoromethylphenyl-mercapto)diphenyl ether 3 ,3 -bis(p-trifiuoromethylphenylmercapto) diphenyl ether 3 3 '-'b iso-trifiuoromethylphenylmercapto diphenyl ether 3 ,3 -bis(m-methoxyphenylmercapto diphenyl ether 3,4'-bis(m'isopropoxyphenylmercapto diphenyl ether 3 ,4'-bis (m-perfiuorobutylphenylmercapto diphenyl ether2-(m-tolyloxy-2-phenylmercaptodiphenyl sulfide 2- (p-tolyloxy) -3-phenylmercaptodiphenyl sulfide 2- o-tolyloxy)-4'-phenylmercaptodiphenyl sulfide 3- m-tolyloxy) -3 '-phenylmercaptodiphenyl sulfide 3 m-tolyloxy) -4'-phenylmercaptodiphenyl sulfide 4-m-tolyloxy) -4'-phenylmercaptodiphenyl sulfide3-xylyloxy-4'-phenylmercaptodiphenyl sulfide3-xylyloxy-3-phenylmercaptodiphenyl sulfide 3 -phenoxy-3 m-tolylmercaptodiphenyl sulfide 3 -phenoxy-4'- m-tolylmercapto diphenyl sulfide2-phenoxy-3 (p-tolylmercapto diphenyl sulfide 3-pl1enoxy-4'-(m-isopropylphenylmercapto diphenyl sulfide 3 -phenoxy-3m-isopropylphenylmercapto) diphenyl sulfide 3-m-toloxy-3'-(m-isopropylphenylmercapto) diphenyl sulfide 4-m-trifluoromethylphenoxy) -4'-phenylmercaptodiphenyl sulfide 3-(m-trifluoromethylphenoxy) -4-phenylmercaptodiphenyl sulfide 2-(m-trifluoromethylphenoxy) -3'-phenylmercaptodiphenyl sulfide 3-m-trifluoromethylphenoxy -3 '-phenylmercaptodiphenyl sulfide 3-(p-chlorophenoxy) -3-phenylmercaptodiphenyl sulfide 3- (m-bromophenoxy)-4'-phenylmercaptodiphenyl sulfide bis [m- (m-chlorophenoxy) phenyl]sulfide m-bis 3- (p-methylphenylmercapto) phenoxy] benzene m-bis [3-(m-trifluoromethylphenoxy) phenylmercapto] benzene m-bis [3(m-bromophenoxy phenylmercapto] benzene 3,3 '-bis [m-(p-methylphenylmercapto) phenoxy] diphenyl sulfide 3 ,4'-bis [m-(p-methylphenylmercapto phenoxy] diphenyl sulfide3-(p-xenyloxy)-3'-phenylmercapto diphenyl sulfide,

and the like and mixtures thereof. It is also contemplated within thescope of this invention to employ mixtures of polyphenylether-thioethers as base stocks.

The compositions of this invention are useful as lubricants underextreme conditions. The compositions are especially useful for steel onsteel lubrication.

The phenoxyphenylphosphinic acids of this invention are prepared byinteraction of a phosphine of the formula wherein R R m and a are asdefined above with ethyl alcohol and water.

The interaction is carried out in the absence of a solvent by heatingthe admixture of the three components at temperatures up to andincluding reflux temperature. Pressure is not critical andsubatmospheric, atmospheric and superatmospheric pressures can beemployed. It is generally preferred to slowly add the phosphine to theethyl alcohol and then to add the water to the admixture of phosphineand ethyl alcohol prior to heating. After reaction is complete,generally a period not exceeding more than or minutes, the excess ethylalcohol and water are removed by azeotropic distillation with anazeotroping agent such as benzene.

The separation of the desired phosphinic acid from the azeotroping agentis readily accomplished by conventional means well known to the art. Forexample, distillation, fractional distillation under reduced pressure,selective extraction, fractional distillation using a carrier gas, filmdistillation, evaporation, elution, or any suitable combination of thesemethods.

Dichlorophenoxyphenylphosphines can be prepared by Friedel-Craftcondensation of diphenyl ethers with phosphorus trichloride inaccordance with the procedure set forth in Organic Synthesis, 31, p. 88(1951).

The following examples serve to further illustrate the invention. Allparts are parts by weight unless otherwise expressly set forth.

EXAMPLE 1 This exampyle describes the preparation ofp-phenoxyphenylphosphiuic acid. One part ofdichloro-p-phenoxyphenylphosphine (B.P. 13 8-143 C./0.5 mm. Hg) is slow-1y added to five parts of absolute etyhl alcohol in a suitable vesseland then two parts of water are added to the alcohol phosphine admixturewith continuous stirring. The resulting admixture is heated at refluxfor about five minutes. Evaporation of alcohol and water produces anoily substance. Residual alcohol and water are removed EXAMPLE 2 Apolyphenyl thioether-polyphenyl ether-thioether lubricant composition isprepared by combining p-phenoxyphenyl phosphinic acid (0.10 gram) withgrams of a thioether of the following composition:

Percent by wt. Meta-bis (phenylmercapto)benzene 50Bis(m-phenoxyphenyl)sulfide 12.5 (m-Phenoxyphenyl) (mphenylmercaptophenyl) sulfide 23.5 Bis (m-phenylmercaptophenyl)sulfide12.65 3 ring and 5 ring thioethers 1.35

and containing 10 parts per million of a dimethyl silicone antifoamagent (Dow-Corning-ZOO, 350 cs. fluid). After stirring at 40 C. todissolve the acid, the mixture is cooled to room temperature andfiltered.

The resultant admixture was tested for lubricity with a slow speed fourball machine. A slow speed four ball machine measures the boundarylubricity action of additives. This test is a variation of the wellknown Shell Four Ball Test in which a ball is rotated against threestationary balls. Wear scars and/or seizure loads measure additivelubricity. In the slow speed instrument the three stationary balls arereplaced with cincular discs. Standard operating conditions are:

3 kg. load 1 r.p.m. Room temperature to 700 F.

The speed of rotation is very low, namely one r.p.m. This equals 0.88inch/minute. This is done for two reasons. It insures boundaryconditions, i.e., metal to metal contact. It also eliminates metal skintemperature flashes which can occur at high speeds. Thus the bulk oiltemperature is equivalent to the metal surface temperature. Under theseconditions wear is negligible and friction is used to followlubrication. After covering the ball and disc with the test oil, theinitial friction is recorded. The test sample is then heated at 700 F.with continuous recording of the friction. This gives a boundaryfriction-temperature profile for the experimental fluid over thistemperature range. The base stock was also tested for control purposes.When the mixture of Example 2 was tested by this procedure on M-50 toolsteel, the observed coefficient of friction was substantially lower thanthat for the base fluid over the temperature range from 340 F. to 700 F.Moreover a decrease in the coefficient of friction began at 340 F. withthe resultant admixture and not until 480 F. with the base stock.

The decrease in coeflicient of friction indicates an improvedperformance in Falex tests for the compositions of this invention.

The embodiments of this invention in which an exclusive property orprivilege is claimed are defined as follows:

1. Composition comprising a major amount of a polyphenyl thioetherhaving the formula wherein R is phenyl or a substituted phenyl, R isphenylene or substituted phenylene, in which the substituents of saidphenyl and phenylene are halogen, alkyl or alkoxy containing from 1 to 4carbon atoms, 11 is an integer of from 1 to 6, Y is sulfur or oxygenprovided that at least one Y is sulfur, and mixtures of such thioethersand from 7 about 0.01 to about 0.5% by weight of aphenoxyphenylphosphinic acid compound of the formula wherein R and R arealkyl of not more than 4 carbon atoms, haloalkyl of not more than 4carbon atoms and 3 halogen atoms, halogen, hydroxyl or phenyl, and m anda are integers from 0 to 3.

2. Composition of claim 1 wherein the phenoxy-phenylphosphinic acid ispresent in amounts of from about 0.05 to about 0.2% by weight.

3. Composition of claim 1 wherein m and a are 0.

4. Composition of claim 1 wherein m is 1, R is alkyl and a is 1 and R isalkyl.

5. Composition of claim 4 wherein the alkyl is methyl.

6. Composition of claim 1 wherein the compound isp-phenoxyphenylphosphinic acid.

8 7. Composition of claim 1 wherein the compound iso-phenoxyphenylphosphinic acid.

References Cited UNITED STATES PATENTS DANIEL E. WYMAN, Primary ExaminerW. H. CANNON, Assistant Examiner US. Cl. X.R.

PC4050 I UNITEU STATES PATENT @FFKQE (5/69) t u m QE'llFi-(IATE @F CREQi? l@ Patent No. 3 $714,043 Dated January 30, 1973 Inventor) Frank S.Clark It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

w Column 1, in the formula beginning at line 53 "R shbuld read R Columnl,' in the formula beginning at line 53 "R I should read R I Column 2,'in the formula beginning at line 61 "R should read R Signed and sealedthis 3rd day Of'July' 1973,

(SEAL) Attest:

EDWARD MELETCHERJR. Rene Tegtme'yer Attestfmg ev Acting Commissioner ofPatents

